package com.PAT.UnSatisfying;

import java.text.DecimalFormat;
import java.util.Scanner;

/**
 * Created with IntelliJ IDEA.
 *
 * @Author: zjz
 * @Date: 2021/11/30/13:50
 * @Description:
 * @Target:
 */
public class 计算谱半径 {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int N = in.nextInt();

        double sum = 0;
        double max = Integer.MIN_VALUE;

        while (N-->0){
            int x = in.nextInt();
            int y = in.nextInt();

            sum = x*x + y*y;
            sum = Math.sqrt(sum);

            max = Math.max(max, sum);
        }


        DecimalFormat df = new DecimalFormat("#0.00");


        System.out.println(df.format(max));



    }


}
